Polycrystalline diamond tools and method of making thereof

ABSTRACT

The present invention is a tool insert. The tool insert includes a abrasive layer and a substrate. The abrasive layer has a periphery forming a cutting surface and is located on the substrate. The abrasive layer includes at least one of polycrystalline diamond or cubic boron nitride. The abrasive layer tool insert has a sum value of an impact resistance number and an abrasion resistance number that is ≧19,000. The impact resistance number is equal to a total number of hits before failure of the tool insert. The abrasion resistance number is equal to equation (1) (1) abrasion resistance=final volume of granite removed by the tool insert (inch 3 )/final tool wear land area (inch 2 ).

CROSS REFERENCE OF RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication No. 60/467,311 filed May 2, 2003, which is herebyincorporated by reference in its entirety.

BACKGROUND

1. Field of the Invention

The present invention generally relates to polycrystalline diamond toolsand method of manufacturing thereof. More particularly, the presentinvention relates to polycrystalline diamond tools having increasedimpact and abrasion resistance properties.

2. Description of Related Art

Polycrystalline diamond (“PCD”) tools are used extensively in drilling,cutting, and machining applications. Extensive efforts have been made toimprove the abrasion resistance and impact resistance properties. Largediamond grain size leads to high impact resistance but relatively lowabrasion resistance for drilling cutters. Alternatively, fine diamondgrain size is utilized for increased abrasion resistance which leads todecreased impact resistance.

It has been a challenge to achieve both high impact resistance andabrasion resistance for polycrystalline diamond tools. The effect ofgrain size dependence on the performance of polycrystalline diamonddrilling cutters has been extensively investigated. Different fromnormal ceramics such as alumina and silicon carbide, whose fracturetoughness increases with decreasing grain size, fracture toughness ofPCD, which determines the impact resistance of the cutter, actuallydecreases with finer diamond. grain size as disclosed in Miess, D. andRai, G., Fracture Toughness and Thermal Resistance of PDC, MaterialsScience and Engineering, A29,270-276, 1996.

Therefore, to avoid severe diamond table failure such as delaminationand spalling in high impact drilling applications, a coarse grain sizemicrostructure is desired. However, with the larger grain size, abrasionresistance is sacrificed, thereby limiting the lifetime of the cutterdue to the fast wear of the diamond table. Various attempts have beenmade to address this concern by varying the diamond table configuration.For example, U.S. Pat. No. 4,311,490 describes a non-uniform diamondtable configuration including an upper fine grain layer and a lowercoarse grain layer. U.S. Pat. No. 4,604,106 proposes a PCD compactcomprising a transition layer with a diamond-carbide composite between anormal carbide substrate and a working PCD layer. Another example is EPPatent Application No. 1190791 which describes a non-uniformmicrostructure with gradient distribution of catalyzing materials. Withthese non-uniform microstructures, the fracture toughness of the portionof diamond table close to supporting substrates can be improved.Consequently, the top portion of diamond table remains brittle and has atendency to fail under high impact.

U.S. Pat. No. 5,766,394 describes some examples made with a particlesize distribution including three different average particle sizes, withthe particle size distribution showing a continuous size variation. U.S.Pat. No. 6,261,329 proposes a diamond sintered body consisting ofparticles with sizes ranging from 0.1 micron to 70 microns, havingcontinuous particle size distribution. U.S. Patent Application No.20040062928 proposes a machining tool made of a bimodal powder mixtureand a certain amount of binder-catalyst. U.S. Pat. Nos. 5,468,268 and5,505,748 describe a tri-modal powder mixture to make a PCD compact.Based on the example provided by U.S. Pat. No. 5,505,748, the calculatedrelative density of packing body will be between 0.66-0.72 using theextended Westman model (See Westman, A. E. R., and Hugill, H. R., ThePacking of particles, J. Am. Ceram. Soc., 13[10], 767-769, 1930). U.S.Pat. No. 5,855,996 describes a mixture of an average size with submicronsized diamond particles and large sized particles.

Accordingly, a need exists for tools or tool inserts that providecombined increased impact and abrasion resistance, including themanufacturing of an optimum powder mixture with shape and volumefraction controlled fine particles and coarse particles, that overcomesthe disadvantages of the single size diamond grain microstructure andimproves the overall performance of the tools with respect to combinedabrasion resistance and impact resistance properties.

SUMMARY

The present invention relates to cutting elements, comprising sinteredpolycrystalline diamond or cubic boron nitride (cBN) starting from afeed of bimodal powder mixture of two different types of single sizeparticles. The cutting elements or tool inserts may be utilized indrilling, machining, milling or cutting applications and the like. Theinvention further relates to improving the impact resistance and/orabrasion resistance of cutting elements by the use of PCD or cubic boronnitride starting from a bimodal powder mixture of two different types ofsingle size or substantially uniform particles.

An embodiment of the present invention is directed to a tool insert. Thetool insert includes a abrasive layer and a substrate. The abrasivelayer has a periphery forming a cutting surface and is located on thesubstrate. The abrasive layer includes at least one of polycrystallinediamond or cubic boron nitride. The abrasive layer tool insert has a sumvalue of an impact resistance number and an abrasion resistance numberthat is ≧19,000. The impact resistance number is equal to a total numberof hits before failure of the tool insert. The abrasion resistancenumber is equal to equation (1) $\begin{matrix}{{{{abrasion}\quad{resistance}} = \frac{\begin{matrix}{{final}\quad{volume}\quad{of}\quad{granite}\quad{removed}} \\{{by}\quad{the}\quad{tool}\quad{{insert}\left( {inch}^{3} \right)}}\end{matrix}}{{final}\quad{tool}\quad{wear}\quad{land}\quad{{{area}\left( {inch}^{2} \right)}.}}}\quad} & (1)\end{matrix}$Test methods for abrasion and impact resistance are described in theexamples hereinbelow.

The abrasive layer may be sintered with a high pressure high temperatureprocess. Additionally the abrasive layer is formed from a bimodal powdermixture having at least one of polycrystalline diamond or cubic boronnitride. The bimodal powder mixture includes fine particles of asubstantially uniform size and coarse particles of a substantiallyuniform size. The coarse particles have a different substantiallyuniform size than the substantially uniform size of the fine particles.An average size ratio of fine particles over coarse particles is betweenabout 0.02 and 0.75, preferably between about 0.05 and 0.5, and morepreferably between about 0.1 and 0.5. A standard deviation of particlesize distribution of fine particles and coarse particles may be smallerthan about 0.6 d, preferably 0.5 d, and more preferably 0.4 d, where dis an average particle size. Abrasive crystals of the continuousabrasive layer may have an average aspect ratio of particles of greaterthan about 0.3, preferably greater than about 0.4, and more preferablygreater than about 0.5. A volume fraction of fine particles may bebetween about 5% to 90%, preferably about 10% to 80%, and morepreferably about 15% to 70%. A volume fraction of coarse particles maybe between about 10% to 95%, preferably about 20% to 90%, and morepreferably about 30% to 85%. The abrasive layer may have at least 93vol. % of diamond.

The present invention is also directed to a method for manufacturing atool insert component. In an embodiment, the method includes forming anabrasive layer with a bimodal powder and sintering the abrasive layerwith a high pressure high temperature process. The bimodal powderincludes at least one of polycrystalline diamond and cubic boronnitride. The bimodal powder includes fine particles of a substantiallyuniform size and coarse particles of a substantially uniform size. Thecoarse particles have a different substantially uniform size than thefine particles of substantially uniform size. Abrasive crystals of theabrasive layer may have an average aspect ratio of particles greaterthan about 0.3. The method may also include the step of bonding asubstrate to the abrasive layer.

The abrasive layer in the method has abrasion resistance and impactresistance properties. A sum value of an impact resistance number and anabrasion resistance number is ≧19,000. The impact resistance number isequal to a total number of hits before failure of the tool insertcomponent. The abrasion resistance number is equal to equation (1)$\begin{matrix}{{{{abrasion}\quad{resistance}} = \frac{\begin{matrix}{{final}\quad{volume}\quad{of}\quad{granite}\quad{removed}} \\{{by}\quad{the}\quad{tool}\quad{{insert}\left( {inch}^{3} \right)}}\end{matrix}}{{final}\quad{tool}\quad{wear}\quad{land}\quad{{{area}\left( {inch}^{2} \right)}.}}}\quad} & (1)\end{matrix}$A volume fraction of fine particles may be between about 5% to 90%, anda volume fraction of coarse particles may be between about 10% to 95%.An average size ratio of fine particles over coarse particles may beabout 0.02-0.75.

Another embodiment of the present invention is directed to a tool inserthaving increased abrasion resistance and impact resistance properties.The tool insert includes an abrasive layer and a substrate. The abrasivelayer is formed from a bimodal powder mixture comprising fine particlesof a substantially uniform size and coarse particles of a substantiallyuniform size. Abrasive crystals of the abrasive layer have an averageaspect ratio of particles greater than about 0.3.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph illustrating packing density as a function of measuredparticle aspect ratio for single size diamond particles.

FIG. 2 is a graph illustrating calculated packing densities as afunction of fine particle volume fraction with various particle sizeratio r for bimodal diamond particles.

FIG. 3 is a graph illustrating bimodal powder packing densities as afunction of fine particle volume fraction with a particle size ratio of0.22 and various aspect ratios.

FIG. 4 is a graph illustrating particle size distribution of a bimodalpowder mixture used in one embodiment of the present invention, cutterC.

FIG. 5 is a graph illustrating the performance between the bimodal feedcutter of one embodiment of the present invention and prior artmono-modal feed cutters.

FIG. 6 is a graph illustrating diamond vol% in sintered PCD withmono-modal powder and bimodal powder.

DETAILED DESCRIPTION

The present invention generally relates to tools and/or cutting elementsfor machine wear materials, such as rotary drill bits for use indrilling or coring holes. The present invention may be applied to anumber of different kinds of drill bits, including drag bits, rollercone bits and percussion bits. The tools and/or cutting elements of thepresent invention may also be used in machining, milling, cuttingapplications and the like.

By way of example, the present invention will be primarily described inrelation to a cutting element which includes a preform element, often inthe form of a circular tablet, including a cutting table or abrasivelayer of superhard material having a front cutting face, a peripheralsurface, and a rear face. The abrasive layer may be continuous. The rearface of the cutting table may be bonded to a substrate of material whichis less hard than the superhard material.

The cutting table may include polycrystalline diamond crystals, althoughother hard or superhard materials for example, cubic boron nitride orcombinations thereof may be utilized. The substrate of less hardmaterial may be formed from cemented tungsten carbide, or the like. Thecutting table and substrate are then bonded together during formation ofthe cutting element in a high pressure high temperature (“HPHT”) formingpress for example, as known in the art. The preform cutting element maybe directly mounted on the bit body or may be bonded to a carrier disc,for example also of cemented tungsten carbide, the carrier disc being inturn received in a socket in the bit body. The bit body may be machinedfrom metal, usually steel, or may be formed from an infiltrated tungstencarbide matrix by a powder metallurgy process.

In one embodiment, the substrate may be formed by joining together twoor more disparate carbide discs in the HPHT sintering process to formthe PDC cutter. The carbide discs may vary from each other in bindercontent, carbide grain size, or carbide alloy content. In anotherembodiment, the carbide discs may be selected and arranged to produce agradient of materials content in the substrate which modifies andprovides the properties for the cutting table.

The diamond clusters forming the cutting table are produced by a methodwhich provides a source of carbon and a plurality of growth centerparticles, each growth center particle comprising a bonded mass ofconstituent particles, producing a reaction mass by bringing the carbonsource and the growth center particles into contact with asolvent/catalyst, subjecting the reaction mass to conditions of elevatedtemperature and pressure suitable for crystal growth and recovering aplurality of the diamond clusters, as discrete entities, from thereaction mass. The carbon source may be graphite, HPHT syntheticdiamond, chemical vapor deposited (CVD) diamond or natural diamond, or acombination of two or more thereof or other carbon sources known in theart. Diamond crystals are commercially available from a number ofsuppliers including, for example, Diamond Innovations, Inc. ofWorthington, Ohio.

In the HPHT sintering process, the grain size of PCD is mainlydetermined by the initial or starting diamond particle size. Therefore,by controlling the starting particle size, it is possible to control thefinal microstructure. The impact strength of the PCD body is greatlydependent on the diamond-to-diamond bonding. A high extent ofdiamond-to-diamond bonding is preferred to achieve better performance.This can be accomplished by increasing the starting powder packingdensity. Theoretically, the highest relative density of a single sizesphere packing body is 0.74, and the highest relative density of bimodalpowder packing body, which contains two types of single size particles,is 0.93. Particle shape also affects the packing of the green body.Irregular particle shape usually leads to lower packing density thanthat of perfect spheres.

The dependence of relative density of a diamond powder packing body onparticle shape is determined experimentally. As shown in FIG. 1, forsingle size diamond particles, a particle aspect ratio near 1.0 leads tohigher packing density. Aspect ratio is defined as a ratio of theminimum Feret diameter to the maximum Feret diameter of a particle,where a Feret diameter is the mean value of the distance between pairsof parallel tangents to the projected outline of the particle.Therefore, blocky particles with an aspect ratio close to 1.0 arepreferable to achieve high green body packing density.

The diamond crystals in the present invention have relatively largeaspect ratios. In one embodiment of the invention, the diamond crystalsmay have largely well defined cubo-octahedral shapes. In a secondembodiment, the crystals may have a large aspect ratio in variousshapes, including ellipsoidal. In a third embodiment, the crystals maybe essentially two dimensional such as laminas and/or flakes. In yetanother embodiment, the crystals may be essentially one dimensional, forexample, rod-like, fiber-like and/or needle-like.

The Westman packing model specifically for diamond powder mixture isdeveloped based on the initial single size or substantially uniformparticle packing densities. It shows that high green body packingdensity can be obtained by uniformly mixing two types of particles withcontrolled particle size and shape distribution. FIG. 2 shows therelative density of a diamond powder packing body calculated from thepacking model as a function of volume fraction of two different sizeparticles or bimodal powder and their particle size ratio r, wherer=fine particle size/coarse particle size.

As shown in FIG. 2, the bimodal powder mixture packing density is mainlydependent on the following factors: initial packing density for eachsingle size particles, which is determined by the particle shape,particle size ratio between two different size particles, and volumefraction of each single size powder. FIG. 2 illustrates that a lowerparticle size ratio leads to a higher packing density, thereby meaningthat a greater size difference is preferred for achieving closerpacking. On the other hand, the volume fraction greatly affects thepacking density. It can be seen that for a fixed particle size ratio, abimodal powder mixture with around 70% coarse particles and around 30%fine particles has the highest packing density. With higher green bodypacking density, the powders are crushed less under a HTHP process whichin turn contributes to higher impact resistance.

FIG. 3 illustrates that for a bimodal powder mixture, packing density ishighly dependent on the volume ratio and the aspect ratio of theparticle components, assuming the same particle size ratio. The blockierparticles with aspect ratio close to 1.0 pack better than the moreirregular shaped particles with smaller aspect ratios. The high packingdensity, which is achieved from the particle size ratios, mix ratios andshapes as leads to better tool performance, including impact resistanceand abrasion resistance.

The following tests are described to illustrate the impact resistanceand abrasion resistance properties of exemplary embodiments of cuttingtools of the present invention and comparative prior art samples.

Abrasion Resistance Test: Each sample has a carbide chamfer of greaterthan about 0.2 mm, less than 1.0 mm radial or 45° on the locating base.First, a Barre ray granite log (dimension: φ8-12 inches×L 24 inches,vendor: Rock Of Ages) is fitted to a lathe. The cutter with unchamferedsharp edge is mounted into a steel support. The test area of the cutterpreferably has a planar area no greater than 2×10⁻⁵ inch² prior totesting. The cutter (rake angle: 15 degrees) runs across the rotatinglog with cooling water sprayed to the cutting area. The size of the wearon the cutter is measured by 12× microscope perpendicular to the wearland after each pass of the log. Therefore the measured area is a trueplane area, not an area projected from an angle other than 90 degreesfrom the wear plane. The volume of material removed from the log ismeasured. The values are plotted against each other giving the abrasionresistance of the cutter. The abrasion resistance is calculated as finalvolume (inch³) of the granite removed by the tool divided by the finalwear land area (inch²).

Interrupted Mill Test: This test is to estimate the impact performanceof the cutter on a chamfered sample, with each piece having a carbidechamfer of greater than about 0.2 mm, less than 1.0 mm radial or 45° onthe locating base. The diamond table has a 0.012 inch chamfer by 45°. Inthis test, the cutter (chamfered edge) sample is mounted in a steelholder. The cutter is rotated and cuts in an interrupted fashion andtransverse distance of 0.15 inch through a Wausau granite work piece,(the cutting plane area of the block is about 16 inches long×6.375inches high, vendor: Cold Spring Granite). No cooling liquid is usedduring the test. The test is stopped when the diamond table fails,typically when the worn cutting area reaches the interface between thediamond table and the substrate and the number of impacts (entries intothe log) counted. This is determined optically with 1×.

It has been determined that the abrasive layer of a tool insert or thelike demonstrates increased impact resistance and abrasion resistancewhen the following defined relationship is satisfied:impact resistance number+abrasion resistance number≧19,000Preferably, the sum value of the impact resistance number and theabrasion resistance number ≧20,000. The impact resistance number is thetotal number of impact hits before tool failure. The abrasion resistancenumber is calculated as the final volume (inch³) of the granite removedby the tool divided by the final wear land area (inch²). As discussedhereinabove, such properties are achieved by the bimodal powder havingfine particles of a uniform size and coarse particles of uniforms size,with the fine particles and coarse particles varying in shape to yieldhigh diamond phase density. This will be further demonstrated with thefollowing examples.

EXAMPLE

The examples below are merely representative of the work thatcontributes to the teachings of the present invention, and the presentinvention is not to be restricted by the examples that follow.

In the examples, two types of PCD diamond particles commerciallyavailable from Diamond Innovation of Worthington, OH, having particleswith an average particle size of about 85 micron and about 20 micron aremixed uniformly. The experimental packing density of the powder mixtureis illustrated in FIG. 3. It can be seen that the shape-optimizedbimodal powders can increase the packing density by up to 20% comparedto a single particle size or substantially uniform powder. The particlesize distribution of a typical bimodal powder mixture is shown in FIG.4. The tool is sintered by normal HTHP process.

The abrasion resistance of the tool is measured by granite-log wear testas described above. The test sample has a cylinder shape with a diameterof 13 mm and a height of 13 mm. The diamond table thickness is 2.5 mm.The cutting edge of test part is initially sharp without chamfering.Test is performed on an 8-12 inches diameter granite-log installed on alathe. The rotation speed of granite log is controlled with constantsurface moving speed: 300 SFPM (Surface Feet Per Minute). The cuttingtool has 15 degrees of rake angle and moves parallel to the center-lineof the log with cooling water sprayed to the cutting area. Cutting depthof the tool into the granite log is 0.01 inch. The cross-feed is 1.5inch/min. The wear land area is measured every 2 minutes and the teststopped after 18 minutes. The abrasion resistance is calculated as finalvolume (inch³) of the granite removed by the tool divided by the finalwear land area (inch²).

The impact resistance is characterized by interrupting impact testperformed on Interrupted Mill test machine as described above. Sampleshave the same geometry as those for abrasion test, with the exception ofthe chamfer. Each sample has a 0.012 inch, 45 degrees circumferentialchamfer on the test edge. The sample is held by a tool holder spinningat 320 RPM. The tool cuts into a granite block with a depth of 0.15 inchand 15 degrees rake angle. Each granite block is 16 inches long andmoves along the cutting plane with a speed of 2.1 inch/min. A pass iscomplete when the tool has cleared the block. After each pass, thegranite block is moved back to the starting point and moved toward thecutting tool to establish a new 0.15 inch cutting depth. The impactresistance is then measured by the number of the times the tool engagesor “hits” the granite block before the tool fails. Tool failure isdefined by when the diamond table has been worn to the point that thetungsten carbide substrate is exposed. For this described test, eachpass or “hit” represents an impact resistance of 2080. For example, ifthe tool engages the block five (5) times prior to failure, impactresistance is determined to be (5×2080), 10,400.

With the shape, particle size ratio, and volume fraction optimizedbimodal powder mixture, the performance of the PCD cutting tool ishighly improved as demonstrated. The impact resistance number in Table 1represents the overall hit number on the cutter before the cutter losescutting efficiency and fails. The abrasion resistance number in Table 1represents the tool efficiency defined as the ratio of the removedgranite materials volume over the wear land area of the cutter. Highertool efficiency means better abrasion resistance.

Cutter A and B represent comparable/standard cutters made of traditionalsingle size or substantially uniform particles commercially availablefrom various sources, including Diamond Innovations of Worthington,Ohio. A is made of coarse particles with an average size of 85 micronand an average particle aspect ratio of 0.81. B is made of fineparticles with an average particle size of 20 micron and an averageparticle aspect ratio of 0.67. The particle size distributions for bothpowders were controlled so that the standard deviations of particle sizedistributions are less than 0.3 d, where d is average particle size.Cutter C is made from the bimodal feeds of the present invention bymixing the substantially uniform coarse particles used in Cutter A andthe substantially uniform fine particles used in cutter B.

Table 1 shows the impact resistance and abrasion resistance of threedifferent cutters. As shown in Table 1, compared to standard singlecoarse particle size cutter A, cutter C with bimodal particles maintainshigh impact resistance and has three times higher abrasion resistance.Compared to standard single fine particle size cutter B, cutter C withoptimized bimodal particles has 50% higher impact resistance and 20%higher abrasion resistance. TABLE 1 Summary of impact resistance andabrasion resistance of cutters A, B and C. Coarse Fine Particle ParticleImpact Abrasion Particle vol % Particle vol % Size Ratio Aspect RatioResistance Resistance A: Standard Cutter with 100% 0 — 0.81 15029 2731uniform coarse size particle B: Standard Cutter with 0 100%  — 0.6710500 7500 uniform fine size particle C: Optimized Bimodal  40% 60% 0.22 Average 15600 10048 Cutter Example 1 0.73

FIG. 5 illustrates impact resistance v. abrasion resistance for bimodalcutters and mono-modal cutters. The dashed line of FIG. 5 represents thesum value of the impact resistance number on the y-axis and the abrasionresistance number on the x-axis being equal to 19,000. The mono-modalcutters typically utilized in industry and prior art have an impactresistance number+abrasion resistance number sum below 19,000 or to theleft of the dashed line. The high performance bimodal cutters havevalues to the right of the dashed line, thereby demonstrating impactresistance number +abrasion resistance number ≧19,000, preferably≧20,000 and thereby demonstrating the desired properties.

Additionally, FIG. 6 illustrates a diamond vol. % of cutter B, startingfrom the single modal powder and cutter C, starting from the bimodalpowder in a sintered state. The diamond volume fraction is calculated bycomparing the measured density of the sinter PCD to the single crystaldiamond density. In particular, FIG. 6 illustrates the diamond volumepercentage in the final sintered PCD tool starting from differentdiamond powder. Cutter C having the bimodal powder demonstrates a higherdiamond volume fraction 93.3%. Conversely, cutter B, with the singlemodal powder demonstrates a lower diamond content 90.6%.

In another embodiment, the present invention is directed to a method formanufacturing a tool insert component. The method includes forming anabrasive layer with a bimodal powder and sintering said abrasive layerwith a high pressure high temperature process. The bimodal powderincludes at least one of polycrystalline diamond and cubic boronnitride. The bimodal powder includes fine particles of a substantiallyuniform size and coarse particles of a substantially uniform size. Thecoarse particles have a different substantially uniform size than thefine particles of substantially uniform size. Abrasive crystals of theabrasive layer may have an average aspect ratio of particles greaterthan about 0.3. The method may also include the step of bonding asubstrate to the abrasive layer.

The abrasive layer in the method has abrasion resistance and impactresistance properties. A sum value of an impact resistance number and anabrasion resistance number is ≧19,000. The impact resistance number isequal to a total number of hits before failure of the tool insertcomponent. The abrasion resistance number is equal to equation (1)$\begin{matrix}{{{{abrasion}\quad{resistance}} = \frac{\begin{matrix}{{final}\quad{volume}\quad{of}\quad{granite}\quad{removed}} \\{{by}\quad{the}\quad{tool}\quad{{insert}\left( {inch}^{3} \right)}}\end{matrix}}{{final}\quad{tool}\quad{wear}\quad{land}\quad{{{area}\left( {inch}^{2} \right)}.}}}\quad} & (1)\end{matrix}$A volume fraction of fine particles may be between about 5% to 90%, anda volume fraction of coarse particles may be between about 10% to 95%.An average size ratio of fine particles over coarse particles may beabout 0.02-0.75.

In yet another embodiment, the present invention is directed to a toolinsert having increased abrasion resistance and impact resistanceproperties. The tool insert includes an abrasive layer and a substrate.The abrasive layer is formed from a bimodal powder mixture comprisingfine particles of a substantially uniform size and coarse particles of asubstantially uniform size. Abrasive crystals of the abrasive layer havean average aspect ratio of particles greater than about 0.3.

While the present invention is satisfied by embodiments in manydifferent forms, there is shown in the drawings and described herein indetail, the preferred embodiments of the invention, with theunderstanding that the present disclosure is to be considered asexemplary of the principles of the invention and is not intended tolimit the invention to the embodiments illustrated. Various otherembodiments will be apparent to and readily made by those skilled in theart without departing from the scope and spirit of the invention. Thescope of the invention will be measured by the appended claims and theirequivalents.

1. A tool insert comprising: a abrasive layer having a periphery forminga cutting surface wherein said continuous abrasive layer comprises atleast one of polycrystalline diamond or cubic boron nitride; and asubstrate, said abrasive layer being located on said substrate, whereinsaid abrasive layer tool insert has a sum value of an impact resistancenumber and an abrasion resistance number ≧19,000, wherein the impactresistance number is equal to a total number of hits before failure ofthe tool insert and the abrasion resistance number is equal to equation(1) $\begin{matrix}{{{{abrasion}\quad{resistance}} = \frac{\begin{matrix}{{final}\quad{volume}\quad{of}\quad{granite}\quad{removed}} \\{{by}\quad{the}\quad{tool}\quad{{insert}\left( {inch}^{3} \right)}}\end{matrix}}{{final}\quad{tool}\quad{wear}\quad{land}\quad{{{area}\left( {inch}^{2} \right)}.}}}\quad} & (1)\end{matrix}$
 2. The tool insert of claim 1, wherein said abrasive layeris sintered with a high pressure high temperature process.
 3. The toolinsert of claim 1, wherein said abrasive layer is formed from a bimodalpowder mixture having at least one of the polycrystalline diamond orcubic boron nitride.
 4. The tool insert of claim 3, wherein the bimodalpowder mixture comprises fine particles of a substantially uniform sizeand coarse particles of a substantially uniform size, said coarseparticles having a different substantially uniform size than thesubstantially uniform size of the fine particles.
 5. The tool insert ofclaim 4, wherein an average size ratio of fine particles over coarseparticles is between about 0.02 and about 0.75.
 6. The tool insert ofclaim 4, wherein an average size ratio of fine particles over coarseparticles is between about 0.05 and about 0.5.
 7. The tool insert ofclaim 4, wherein an average size ratio of fine particles over coarseparticles is between about 0.1 and about 0.5.
 8. The tool insert ofclaim 4, wherein a standard deviation of particle size distribution offine particles and coarse particles is smaller than about 0.6 d, where dis an average particle size.
 9. The tool insert of claim 4, whereinabrasive crystals of said abrasive layer have an average aspect ratio ofparticles of greater than about 0.3.
 10. The tool insert of claim 4,wherein abrasive crystals of said abrasive layer have an average aspectratio of particles of greater than about 0.4.
 11. The tool insert ofclaim 4, wherein abrasive crystals of said abrasive layer have anaverage aspect ratio of particles of greater than about 0.5.
 12. Thetool insert of claim 4, wherein a volume fraction of fine particles isbetween about 5% to 90%, and a volume fraction of coarse particles isbetween about 10% to about 95%.
 13. The tool insert of claim 4, whereina volume fraction of fine particles is between about 10% to 80%, and avolume fraction of coarse particles is between about 20% and about 90%.14. The tool insert of claim 4, wherein a volume fraction of fineparticles is between about 15% to 70%, and a volume fraction of coarseparticles is between about 30% and about 85%.
 15. The tool insert ofclaim 3, wherein said abrasive layer has at least about 93 vol. % ofdiamond.
 16. A method for manufacturing a tool insert componentcomprising: forming an abrasive layer with a bimodal powder comprisingat least one of polycrystalline diamond and cubic boron nitride, saidbimodal powder comprising fine particles of a substantially uniform sizeand coarse particles of a substantially uniform size, said coarseparticles having a different substantially uniform size than the fineparticles of substantially uniform size, wherein abrasive crystals ofsaid abrasive layer have an average aspect ratio of particles greaterthan about 0.3; and sintering said abrasive layer with a high pressurehigh temperature process.
 17. The method according to claim 16, furthercomprising the step of bonding a substrate to said abrasive layer. 18.The method according to claim 16, wherein said abrasive layer havingabrasion resistance and impact resistance properties, has a sum value ofan impact resistance number and an abrasion resistance number ≧19,000,wherein the impact resistance number is equal to a total number of hitsbefore failure of the tool insert and the abrasion resistance number isequal to equation (1) $\begin{matrix}{{{{abrasion}\quad{resistance}} = \frac{\begin{matrix}{{final}\quad{volume}\quad{of}\quad{granite}\quad{removed}} \\{{by}\quad{the}\quad{tool}\quad{{insert}\left( {inch}^{3} \right)}}\end{matrix}}{{final}\quad{tool}\quad{wear}\quad{land}\quad{{{area}\left( {inch}^{2} \right)}.}}}\quad} & (1)\end{matrix}$
 19. The method of claim 16, wherein a volume fraction offine particles is between about 5% to 90%, and a volume fraction ofcoarse particles is between about 10% and about 95%.
 20. The method ofclaim 16, wherein an average size ratio of fine particles over coarseparticles is about 0.02 to about 0.75.
 21. A tool insert havingincreased abrasion resistance and impact resistance properties,comprising an abrasive layer and a substrate, wherein said abrasivelayer is formed from a bimodal powder mixture comprising fine particlesof a substantially uniform size and coarse particles of a substantiallyuniform size, wherein abrasive crystals of the abrasive layer have anaverage aspect ratio of particles greater than about 0.3.